Many different types of knives are known such as those having a stationary knife blade which must be stored in a knife sheath when not being used. Other types of knives are known such as a typical pocket knife in which the knife blade must be manuevered from a retracted position to an operating position. Of course this manual operation requires two hands. Also knives are known in which the blade, in its retracted position, is under a tension force such as by means of a spring or otherwise and which is released such as by pressing a button or the like. Various examples of these types of knives are disclosed in the following U.S. Pat. Nos. 587,692, 690,927, 1,478,260, 1,495,449, 1,864,011, 2,250,290, 4,233,106, 4,451,982.